Foster kids should stay in system until 21

Children in foster care should be cared for until they're 21 to give them a better chance at staying out of trouble, Anglicare Victoria has told police.

Speaking at the Chief Commissioner's Youth Summit in Melbourne on Thursday, Anglicare Victoria's chief executive Paul McDonald called for the foster care age limit to be extended.

In Australia, children in care must leave their care placement at 18, while in other countries like the UK, Canada and America, that age limit is 21.

"What we do know is that half of those who leave care - and in Victoria it's about 680 and about 3000 around Australia - will be in jail, unemployed, pregnant or homeless within the first 12 months of them leaving care," Mr McDonald said.

"What I'm proposing is that we continue the care placement because those young people are developmentally not ready, and we should continue care through to 21."

It's a sentiment Chief Commissioner Graham Ashton said he will be considering, as he compiles a report for the state government on youth crime prevention.

"That's been put to us a number of times by people in the system," he said.